De Marigny made his primary residence in New Orleans, but maintained Fontainebleau as a summer retreat away from the crowds and slightly more extreme climate of the big city south of Pontchartrain. (The North Shore has always served as a sort of playground for New Orleanians.) But much as he may have enjoyed country life, he was not about to let the land sit idle. He actively developed the town of Mandeville, just to the west of Fontainebleau, and the plantation itself was one of the first large-scale sugarcane operations in what became the United States. Another of de Marigny's commercial interests was a brick kiln, which presumably furnished the materials for the mill.
But if Bernard de Marigny had a checquered career, consider the political changes that swept through the North Shore (many of which de Marigny lived through):
- Part of French Louisiana until 1763
- Ceded to Great Britain after the French and Indian War, became part of the British territory of West Florida
- Ceded to Spain in 1783
- Became part of the independent Republic of West Florida in 1810
- Annexed by the United States 90 days later
- Louisiana seceded from the United States and became the Republic of Louisiana in 1861
- Louisiana joined the Confederate States of America soon thereafter
- Louisiana once again part of the United States in 1865
That's seven national flags, with one repeat, in just over a century. One of those flags pulled double duty: the flag of the Republic of West Florida resurfaced later, on an unofficial basis, as the Bonnie Blue Flag of the early Confederacy. (Evidence for the two flags representing "relation by descent" as opposed to "convergent similarity" is the fact that the Bonnie Blue made its first appearance in Mississippi, part of which had been included in the Republic of West Florida. Occam's Razor would argue against coincidence, as secession-minded Mississippians might very reasonably turn to an historic symbol of independence from their own relatively recent past.)
Note also that this part of Louisiana, administered by Spain and not France in 1803, was not part of the Louisiana Purchase (though some in the States argued at the time that it was). St. Tammany, in which Fontainebleau is located, and the neighbouring parishes are known as the Florida Parishes.